Here is the full list of all 54 Fallen Enchantress: Legendary Heroes achievements.
Play for 100 hours.
Win by having the highest score by the turn limit.
Win by forging an alliance with all players.
Win as Tarth.
Win as Kraxis.
You've managed to slay Torax!
Recruit Gallowman
Make 1000 gildar from selling items in shops.
Win as Altar.
Recruit Raza the Wild
Win as Umber.
Win as Capitar.
Win as Magnar.
Win by completing the Master Quest.
You've managed to slay Abeix!
You've managed to slay Vetrar!
Play for 40 hours.
Recruit Mausolos
Win as Pariden.
Win by casting the Spell of Making.
Play for 20 hours.
Create a custom sovereign.
Win and have at least 3,000 population.
Win as Gilden.
Win by defeating all of your opponents.
Play for 10 hours.
Complete 10 quests in a single game.
Not since Peter MacNicol has one been slain!
Defeat a faction.
You defeated a sovereign in battle!
You have captured an enemy city!
Get a city to level 5 in one game.
Play for 5 hours.
Design a unit.
Buy an item from a shop.
Reach level 15 with a champion.
Control 5 cities in a single game.
Tap 10 resources in a single game.
Reach level 5 with a champion.
Explore 10 goodie huts in a single game.
Your Fame has lead a hero to your cause.
Complete a quest.
You have defeated an army!
You killed a monster!
All nations start with one.
You've managed to slay Delin!
You've managed to slay Morian!
Awarded for completion of the Legendary Hero scenario.
Win as Resoln.
Win as Yithril.
Recruit Kasst
Recruit Tuatha
Recruit Nen Ratcatcher
Recruit Ascian